Many electronic devices incorporate one or more voltage regulators to convert a system power source voltage level into one or more regulated voltages that are used to bias circuitry within the electronic device. There are a variety of different topologies of voltage regulators, each having unique strengths and weaknesses that are typically taken into account when designing or selecting a voltage regulator for a given application within an electronic device. For example, the level of the load may vary greatly during operation of the electronic device as various functions of the electronic device are activated or deactivated at different times. In such a case, the voltage regulator must be designed to respond to the anticipated changes in load while maintaining its output voltage within the specified limits.
The design of a voltage regulator generally includes the selection of various parameters that depend on the type of the voltage regulator and the anticipated load environment. For example, voltage regulators that are classified as switching regulators use combinations of switches (often embodied as transistors including MOSFETs, BJTs, IGBTs, JFETs, etc), inductors and/or transformers, and capacitors as the basis for step-up and/or step-down voltage conversion. Some voltage regulator design parameters will include the size of the transistors used as switches, the size/inductance of the inductors (or size/turns ratio of the transformers), the size/capacitance of the capacitors, the frequency at which the switches are turned on and off, and the voltage levels selected to turn on/off the switches, among other parameters. Additional parameters including the voltage regulator's input voltage range, output voltage range, and load range will help determine the voltage regulator design parameters.
The efficiency of the voltage regulator generally depends greatly on each voltage regulator design parameter in combination with the input voltage range, output voltage range, and load range, among other factors. However, since the load may vary during operation of the electronic device, it is impossible during the design phase to select ‘fixed’ values for these voltage regulator design parameters that will always result in the highest possible operating efficiency of the voltage regulator. As a result, since these regulator parameters are static, the voltage regulator is almost certain to operate below its highest possible operating efficiency for a significant percentage of the time. This situation occurs even if the most common operating power level of the electronic device is known and the parameters of the voltage regulator are selected accordingly.
In many typical situations, voltage regulators are designed to exhibit their highest efficiency at their highest operating power state. Consequently, they are generally over-designed for the lower power states. In other words, efficiency is significantly lower at the lower power states in these designs. This relationship between efficiency and power state is generally considered acceptable, since it is usually assumed that power loss should be minimized whenever the maximum rated power for the design is approached. However, there is a long-felt need to continue to increase overall power consumption efficiency for almost all electronic devices across the full load range, not just at the maximum rated power specification. However, efficiency improvements have generally been pushed so far as to have reached a level that any additional improvements at the highest power states can only result in relatively minor overall improvements.
Some voltage regulators are considerably less efficient under relatively light load conditions when compared to the efficiency at a ‘normal’ load or even a heavy load. Consequently, many such voltage regulators are designed to change their operating characteristics when a light load state, such as a sleep mode, occurs within the electronic device. Nevertheless, whether the electronic device is in a light load state or a heavy/normal load state, the load may still vary considerably, resulting in inefficient operation of the voltage regulator for a significant percentage of the time.
It is with respect to these and other background considerations that the present invention has evolved.